Filter cigarette

ABSTRACT

The invention relates to a filter cigarette having a filter ( 1 ) that is surrounded by a filter wrapping paper ( 2 ) which is enclosed by a coating ( 3 ) of the tip. The inside of the filter wrapping paper ( 2 ) is coated with a metal, especially aluminium. The coating is only applied to a part of the filter wrapping paper ( 2 ) in such a way that air can penetrate through said paper and into the filter ( 1 ).

[0001] The invention concerns a filter cigarette whose filter issurrounded by a filter wrapping paper which a tip layer encloses,wherein the inside of the filter wrapping paper is coated with metal, inparticular aluminum.

[0002] The development of cigarettes with reduced smoke constituents, inparticular nicotine, condensate and carbon monoxide, has globally beendriven forward by statutory regulations, a higher level of consumeracceptance and increased awareness of health.

[0003] Usually cigarette papers which are highly permeable to air andburning-friendly are used for the production of cigarettes with reducedsmoke constituents and the cigarette filter has been additionally ventedby a perforated zone in the tip layer. Both technical measures dilutethe main smoke flow by virtue of secondary air and thereby reduce thelevel of concentration of the smoke constituents. The use of filtermaterial with a high retention action and a high draw resistance alsocauses a reduction in the smoke constituents, but encounters limitationsin terms of acceptance by consumers.

[0004] In the state of the art, DE 3038093 A1, WO 89/03183 A1 and CH343865 disclose cigarette filters in which metal is introduced into thefilter. That however on the one hand involves a considerable increase inexpenditure in manufacture of the filters, while on the other hand theeffect achieved thereby is only very vaguely described in respect of itseffect.

[0005] Therefore the basic starting point adopted by the invention is afilter cigarette whose filter is surrounded by a filter wrapping paperwhich a tip layer encloses, wherein air can penetrate into the filterthrough the filter wrapping paper. In accordance with the invention itis provided that the coating is applied only on a part of the filterwrapping paper so that air can penetrate therethrough into the filter.

[0006] The metalization effect can be implemented by application inparticle form and/or by suitable application of flat patterns to thewrapping paper on the surface of the paper, but not by complete coatingof the filter wrapping paper. Surprisingly, partial coating of thefilter wrapping paper with metal surfaces causes a selective reductionin the carbon monoxide content of the main smoke flow.

[0007] Further features and details of the present invention will beapparent from the specific description hereinafter. In the drawing:

[0008]FIG. 1 shows a filter wrapping paper according to the inventionwith aluminum strips, and

[0009]FIG. 2 shows a filter wrapping paper according to the inventionwith a finely distributed and highly porous aluminum layer.

[0010] In FIG. 1, aluminum strips have been applied to a commerciallyavailable highly porous paper for wrapping cigarette filters(Papierfabrik Wattens GmbH, QNo 27400) with an air permeability of 6000CU by means of a hot foil process. The width of the wrapping paper was26.5 mm and the width of the aluminum strip was 1 mm. The spacingbetween the strips was 1 mm. Filter rods for cigarettes were produced inper se known manner from a reel measuring about 1000 m in length andwith industrially usual acetate cable. The drawing shows the structureof such a filter rod comprising acetate cable 1, wrapping paper 2 andtip layer 3, while reference 4 denotes the aluminum strips according tothe invention.

[0011] Cigarettes are produced by machine, using those filter rods. Forcomparison purposes, cigarettes were produced on the basis of the samecomposition in terms of filter, cigarette paper and tobacco blend, butwithout previous zone-wise coating of the filter wrapping paper. Thecigarettes produced were smoked away under standardized conditions in asmoking laboratory. The smoke constituents of the main smoke flow have aselectively and significantly lower carbon monoxide content, as shown inTable 1. TABLE 1 Results of standardized smoking of cigarettes with(modified) and without (standard) aluminum strips 4 on the filterwrapping paper 2. Nicotine-free dry Draw Nicotine condensate number(mg/cig) (mg/cig) CO (mg/cig) Modified 8.42 (8.44) 0.61 (0.64) 8.37(8.31) 9.04 (8.58) filter wrapping paper Standard 8.12 (8.24) 0.63(0.64) 9.06 (9.08) 11.86 (10.96) filter wrapping paper

[0012] The brackets show the results of a second independent measurementseries.

ÖZF: Österreichische Zigarettenfilter GmbH, Hainburg/Donau

[0013]FIG. 2 shows another embodiment according to the invention. Here,with the structure of the filter rod otherwise being the same in regardto the acetate cable 1 and the tip layer 3, the filter wrapping paper 2was coated in finely distributed form with aluminum, but here thealuminum layer 5 was highly porous. This kind of aluminum coatingensures that the air permeability of the filter wrapping paper is stillsufficiently maintained so that, as also in the embodiment of FIG. 1,sufficient air can pass laterally into the cigarette filter.

[0014] For comparison purposes and to demonstrate the action of thehighly porous aluminum layer 5, besides the embodiments according to theinvention as shown in FIG. 2, otherwise identical cigarette filters werealso produced without the aluminum coating 5 according to the inventionon the wrapping paper 2. Those filter rods were used to produce bymachine otherwise equivalent cigarettes with and without the coating 5according to the invention. The cigarettes produced therefore differonly in regard to the presence of the coating 5 according to theinvention. The cigarettes produced in that way, as in the case of theembodiment in FIG. 1, were also smoked away under standardizedconditions in a smoking laboratory. The measured smoke constituents ofthe main smoke flow also have a selectively and significantly lowercarbon monoxide content and therefore the same effect as in the firstembodiment. Table 2 shows the results of measurement of the sameparameters as in Table 1, but in a comparison between cigarettes with astandard filter wrapping paper and with the filter wrapping paper 2according to the invention which is coated with a finely distributedhighly porous aluminum layer 5. TABLE 2 Results of standardized smokingof cigarettes with (modified) and without (standard) finely distributedhighly porous aluminum coating 5 on the filter wrapping paper 2.Nicotine-free Nicotine dry condensate CO Draw number (mg/cig) (mg/cig)(mg/cig) Modified filter 7.71 0.43 7.67 11.33 wrapping paper Standardfilter 7.99 0.46 7.62 14.26 wrapping paper

[0015] Clearly the invention combines the known advantage of filterventing with an effect which is to be attributed to the metal coating.In that respect the two embodiments show that the effect can bedemonstrated, irrespective of the nature of the metal coating, as longas the combination recited in claim 1 of air permeability of the filterwrapping paper and the metal coating of the filter wrapping paper isguaranteed. This makes it clear that in that sense the invention is notlimited to the illustrated embodiments, but includes all possiblecombinations of the embodiments shown herein and other embodiments inaccordance with claim 1.

[0016] The physical or chemical mechanism to which that effect is to beattributed still remains to be investigated. A possible explanationwould be the adsorption of carbon monoxide on the metal, whereas apurely catalytic action, because of the low temperature in the filter,is improbable.

1. A filter cigarette whose filter is surrounded by a filter wrappingpaper which a tip layer encloses, wherein the inside of the filterwrapping paper is coated with metal, in particular aluminum,characterized in that the coating is applied only to a portion of thefilter wrapping paper (2) so that air can penetrate therethrough intothe filter (1).
 2. A filter cigarette as set forth in claim 1characterized in that metal coating comprises aluminum.
 3. A filtercigarette as set forth in claim 1 or claim 2 characterized in that themetal coating comprises longitudinally extending strips (4).
 4. A filtercigarette as set forth in one of claims 1 through 3 characterized inthat the metal coating (5) is applied in finely distributed and highlyporous form to the filter wrapping paper (2).